The present invention relates generally to the field of bladder control devices. More particularly, the invention relates to the field of bladder control devices in which a valve is provided to control flow from the bladder of a patient.
Bladder control devices related to the field of this invention include devices such as those disclosed by Kulisz et al., in U.S. Pat. No. 5,512,032 and U.S. Pat. No. 5,701,916. The former patent discloses a bladder control device including a valve which remains open under the influence of flow through the device in accordance with Bernoulli""s Principle. The latter patent discloses proximally and distally disposed retainers for retaining the bladder control device within a patient""s urethra. These pioneering devices can be activated in an intuitive way by a patient, simply by the patient increasing bladder pressure. The valve remains open at a lower pressure so long as a certain minimal flow rate through the valve continues. When the flow subsides, the valve closes.
Intraurethral bladder control devices are disposed within the urethra during use. Consequently, patients and their physicians desire that the diameter of the device be limited without compromising the performance of the device. It can be appreciated that larger diameter bladder control devices could cause some discomfort during insertion and use. Scaling down a device, i.e., making a smaller device having the same configuration, will reduce the flow through the device exponentially. Reducing flow through the valve limits the force creatable by the Bernoulli""s Principle to hold the valve open. Additionally, if the diameter of a compression spring, as used in the prior devices to bias the valve close, is scaled down, the spring is subject to buckling, which could leave the valve in a permanently open position.
The present invention pertains to a valve for a bladder control device which incorporates features allowing the device to be effective when produced in small diameters, such as 18F, for example. The valve for a bladder control device in accordance with the present invention includes an elongate housing which has a proximal end and a distal end. A lumen extends through the housing. A valve seat is disposed within the housing and a stopper is disposed within the housing. The stopper is moveable between a first position engaging the valve seat and a second position disposed distally of the valve seat. In the first position, the valve is closed, in the second position the valve is at least partially open.
The valve in accordance with the present invention, preferably includes a tension spring connected to a stopper to bias the stopper toward the valve seat. The spring is under greater tension loading when the stopper is in the second position that when the stopper is in the first position. The spring can include an elongate shaft portion having a proximal end and a distal end. The proximal end of the shaft portion is preferably connected to the stopper and the distal end of the shaft portion is preferably connected to a helical portion of the spring.
The stopper can include a proximal portion having a first diameter generally sized to engage the valve seat. The stopper preferably has a distal portion having a diameter greater than the diameter of the proximal portion.
The lumen through the housing can include a portion disposed distally of the valve seat having a diameter approximately equal to the diameter of the distal portion of the stopper. The stopper is preferably slidably disposed within this portion of the lumen for movement between the first and second positions. A second portion of the lumen, disposed distally of the first portion of the lumen, has a diameter greater than the diameter of the first portion of the lumen. The lumen also preferably includes a third portion disposed distally of the second portion of the lumen which has a diameter less than the diameter of the second portion of the lumen. This region of the lumen, in conjunction with the larger diameter distal portion of the stopper, can induce the desired force in accordance with Bernoulli""s Principle to retain the stopper in the second position so long as a certain minimum flow rate through the lumen is maintained.
The housing in the valve of the present invention preferably has an outer diameter of between about 16F to 22F, and more preferably, about 18F. It can be appreciated, however, that valves having greater or lesser outside diameters may also be made in accordance with the present invention.